Python docx Highlight Matching Text in Microsoft Word Doc

"""Usage : python /home/you/script/this.py file.docx 'phrase to highlight'  # notice the quotes
"""

from docx import Document
from docx.enum.text import WD_COLOR_INDEX
import sys

source = sys.argv[1]
phrase = " ".join(sys.argv[2:]).strip("'")

doc = Document( source )

for para in doc.paragraphs :
start = para.text.find( phrase )
if start > -1 :
pre = para.text[:start]
post = para.text[start+len(phrase):]
para.text = pre
para.add_run(phrase)
para.runs[1].font.highlight_color = WD_COLOR_INDEX.YELLOW
para.add_run(post)

doc.save( source )