Modify docx page margins with python-docx

import docx
from docx.shared import Inches, Cm
doc = docx.Document()
sections = doc.sections
for section in sections:
    section.top_margin = Cm(0.5)
    section.bottom_margin = Cm(0.5)
    section.left_margin = Cm(1)
    section.right_margin = Cm(1)

Here's the code that i used please include from docx.shared import Inches, Cm

Thanks to @tdelaney for pointing out the page where it clearly indicated the solution. I am just posting here the code I used in case anyone else is confused as I initially was:

#Open the document
document = Document(args.inputFile)

#changing the page margins
sections = document.sections
for section in sections:
    section.top_margin = Cm(margin)
    section.bottom_margin = Cm(margin)
    section.left_margin = Cm(margin)
    section.right_margin = Cm(margin)

document.save(args.outputFile)