Populate a .txt document with a CSV spreadsheet using multiple templates, outputting documents for each data row

I'm looking for feedback on functionality, PEP8, advice, etc as a learning tool. I'm not sure how to tell if this program should be broken into separate functions or combined as one.

While hand editing files for an organization I work for, I made this code having seen an opportunity to simplify "How to Integrate Excel Data with Word".

Here are 4 templates simultaneously populated for output documents:

• template all.txt
• special template 1.txt
• special template 2.txt
• mailer.txt

All files are on Google including output files, if that's easier. Git

import csv

def docgen(filename_csv='docgen'):
    open_csv = open(str(filename_csv) + '.csv')
    read_csv = csv.reader(open_csv)
    templates = []
    labels = []
    for row in read_csv:
        if 'docs out' in row[1].lower():
            labels = row[2:]
        elif 'templates in' in row[0].lower():
            templates = row[1:]
            templates = [x for x in templates if x]
        else:
            all_templates = templates[:]
            data_row = row[2:]
            if row[0] != '':
                all_templates.extend([row[0]])
            for template in all_templates:
                if template != '':
                    open_template = open(template + '.txt')
                    doctemp(open_template, template, labels, 
                                 data_row, row)
                    open_template.close()

def doctemp(open_template, template, labels, data_row, row):
    doc_filename = str(row[1]) + ' ' + str(template) + '.txt'
    open_doc = open(doc_filename, 'w')
    for template_line in open_template.readlines():
        doc_line = str(template_line)
        for i, variable in enumerate(labels):
            data = data_row[i]
            data = str(data).strip()
            variable = str(variable).strip()
            if data == '':
                variable_after = variable + ' '
                variable_before = ' ' + variable
                variable_around = ' ' + variable + ' '
                if variable_after in doc_line:
                    doc_line = doc_line.replace(variable_after, '')
                if variable_before in doc_line:
                    doc_line = doc_line.replace(variable_before, '')
                if variable_around in doc_line:
                    doc_line = doc_line.replace(variable_around, '')
                else:
                    doc_line = doc_line.replace(variable, '')
                continue
            if 'units' in variable:
                units = variable.replace(' units', '')
                if data == '1':
                    if units[-1] == 's':
                        units = units[:-1]
                doc_line = doc_line.replace(variable, data + ' ' + units)
            else:
                doc_line = doc_line.replace(variable, data)
        open_doc.write(doc_line)
    open_doc.close()

docgen()

<table>
    <tr>
        <td>Templates in</td>
        <td>template all</td>
        <td></td>
        <td></td>
        <td></td>
        <td></td>
        <td></td>
        <td></td>
        <td></td>
        <td></td>
        <td></td>
        <td></td>
    </tr>
    <tr>
        <td></td>
        <td>Docs out</td>
        <td>title</td>
        <td>first name</td>
        <td>last name</td>
        <td>address 1</td>
        <td>address 2</td>
        <td>dogs units</td>
        <td>donations units</td>
        <td>taxable $</td>
        <td>Organization</td>
        <td>Phone</td>
    </tr>
    <tr>
        <td></td>
        <td>LiamRodriguez</td>
        <td>Mr.</td>
        <td>Liam</td>
        <td>Rodriguez</td>
        <td>100 Main St.</td>
        <td>"Sao Paulo</td>
        <td> Brazil 01000"</td>
        <td></td>
        <td>1</td>
        <td>$100 </td>
        <td>Vets Abroad</td>
        <td>406-243-0211</td>
    </tr>
    <tr>
        <td>special template 1</td>
        <td>LucasPerez PhD.</td>
        <td>Dr.</td>
        <td>Lucas</td>
        <td>Perez PhD.</td>
        <td>200 Main St.</td>
        <td>"Santa Catarina</td>
        <td> Brazil 88000"</td>
        <td>4</td>
        <td>1</td>
        <td>$500 </td>
        <td>Vets Abroad</td>
        <td>406-243-0211</td>
    </tr>
    <tr>
        <td></td>
        <td>NoahGonzalez</td>
        <td>Mr.</td>
        <td>Noah</td>
        <td>Gonzalez</td>
        <td>300 Main St.</td>
        <td>"Rio de Janeiro</td>
        <td> Brazil 20000"</td>
        <td>1</td>
        <td></td>
        <td>$100 </td>
        <td>Vets Abroad</td>
        <td>406-243-0211</td>
    </tr>
    <tr>
        <td>special template 2</td>
        <td>Hernandez</td>
        <td>Dr. & Sir. Ethan</td>
        <td></td>
        <td>Hernandez</td>
        <td>400 Main St. </td>
        <td>"Paraiba</td>
        <td> Brazil 58000"</td>
        <td>5</td>
        <td>2</td>
        <td>$700 </td>
        <td>Vets Abroad</td>
        <td>406-243-0211</td>
    </tr>
    <tr>
        <td></td>
    </tr>
</table>