import hashlib


def GetChecksumsFromFile(filename, hash_fns=None):
  """Computes MD5 and/or other checksums of a file.

  Args:
    filename: Name of the file.
    hash_fns: Mapping of hash functions.
              Default is {'md5': hashlib.md5}

  Returns:
    Mapping of hash names to hexdigest strings.
    { <hashname>: <hexdigest>, ... }
  """
  hash_fns = hash_fns or {'md5': hashlib.md5}
  checksums = {k: fn() for (k, fn) in hash_fns.items()}

  with open(filename, 'rb') as file_handle:
    while True:
      buf = file_handle.read(1048576)  # 1 MiB
      if not buf:
        break
      for hashfn in checksums.values():
        hashfn.update(buf)

  return {k: fn.hexdigest() for (k, fn) in checksums.items()}