def _parse_requirements_file(filename):
  """Parses a requirements.txt file into a list of requirement strings."""
  reqs = []
  with open(filename, "r") as f:
    for line in f.read().splitlines():
      line = line.strip()
      if line.startswith("#"):
        continue
      if not line:
        continue
      reqs.append(line)
  return reqs