Python3: Count lines of code

#!/usr/bin/env python

# This Python script counts the lines of code in the directory in which it is
# run.  It only looks at files which end in the file extensions passed to the
# script as arguments.

# It outputs counts for total lines, blank lines, comment lines and code lines
# (total lines minus blank lines and comment lines).

# Example usage and output:
# > lines_of_code_counter.py .h .cpp
# Total lines:   15378
# Blank lines:   2945
# Comment lines: 1770
# Code lines:    10663

# Change this value based on the comment symbol used in your programming
# language.
commentSymbols = {
    ".cs": "//",        # C#
    ".js": "//",        # JavaScript
    ".sh": "#",         # Bash
    ".ps1": "#",        # Powershell
    ".py": "#",         # Python
    ".Dockerfile": "#", # Docker
    ".md": "<!--",      # Markdown
    ".c": "//",         # C
    ".h": "//",         # C & C++ headers
    ".cpp": "//",       # C++
}

import sys
import os, os.path

acceptableFileExtensions = sys.argv[1:]
if not acceptableFileExtensions:
    print('Please pass at least one file extension as an argument.')
    quit()

currentDir = os.getcwd()

filesToCheck = []
for root, _, files in os.walk(currentDir):
    for f in files:
        fullpath = os.path.join(root, f)
        if '.git' not in fullpath:
            for extension in acceptableFileExtensions:
                if fullpath.endswith(extension):
                    filesToCheck.append(fullpath)

if not filesToCheck:
    print('No files found.')
    quit()

lineCount = 0
totalBlankLineCount = 0
totalCommentLineCount = 0

print('')
print('Filename\tlines\tblank lines\tcomment lines\tcode lines')

for fileToCheck in filesToCheck:
    with open(fileToCheck) as f:

        fileLineCount = 0
        fileBlankLineCount = 0
        fileCommentLineCount = 0

        fileName, fileExtension = os.path.splitext(fileToCheck)
        assert fileExtension in commentSymbols, "Unknown comment symbol for extension '%s'" % fileExtension
        commentSymbol = commentSymbols[fileExtension]

        for line in f:
            lineCount += 1
            fileLineCount += 1

            lineWithoutWhitespace = line.strip()
            if not lineWithoutWhitespace:
                totalBlankLineCount += 1
                fileBlankLineCount += 1
            elif lineWithoutWhitespace.startswith(commentSymbol):
                totalCommentLineCount += 1
                fileCommentLineCount += 1

        print(os.path.basename(fileToCheck) + \
              "\t" + str(fileLineCount) + \
              "\t" + str(fileBlankLineCount) + \
              "\t" + str(fileCommentLineCount) + \
              "\t" + str(fileLineCount - fileBlankLineCount - fileCommentLineCount))


print('')
print('Totals')
print('--------------------')
print('Lines:         ' + str(lineCount))
print('Blank lines:   ' + str(totalBlankLineCount))
print('Comment lines: ' + str(totalCommentLineCount))
print('Code lines:    ' + str(lineCount - totalBlankLineCount - totalCommentLineCount))