def SplitRange(regression):
  """Splits a range as retrieved from clusterfuzz.

  Args:
    regression: A string in format 'r1234:r5678'.

  Returns:
    A list containing two numbers represented in string, for example
    ['1234','5678'].
  """
  if not regression:
    return None

  revisions = regression.split(':')

  # If regression information is not available, return none.
  if len(revisions) != 2:
    return None

  range_start = revisions[0]
  range_end = revisions[1]

  # Strip 'r' off the range start/end. Not using lstrip to avoid the case when
  # the range is in git hash and it starts with 'r'.
  if range_start.startswith('r'):
    range_start = range_start[1:]

  if range_end.startswith('r'):
    range_end = range_end[1:]

  return [range_start, range_end]