text: #! /usr/bin/env python
  """
  constants - General constants of use to fileseq operations.
  """
  
  import re
  
  PAD_MAP = {"#": 4, "@": 1}
  
  # Regular expression for matching a file sequence string.
  # Example: /film/shot/renders/bilbo_bty.1-100#.exr
  SPLIT_PATTERN = r"([-:,xy\d]*)([{0}]+)".format(''.join(PAD_MAP.keys()))
  SPLIT_RE = re.compile(SPLIT_PATTERN)
  
  # Regular expression pattern for matching file names on disk.
  DISK_PATTERN = r"^(.*/)?(?:$|(.*?)(-?\d+)?(?:(\.[^.]*$)|$))"
  DISK_RE = re.compile(DISK_PATTERN)
  
  # Regular expression pattern for matching frame set strings.
  # Examples: '1' or '1-100', '1-100x5', '1-100:5', '1-100y5', '1,2', etc.
  FRANGE_PATTERN = r"^(-?\d+)(?:-(-?\d+)(?:([:xy]{1})(\d+))?)?$"
  FRANGE_RE = re.compile(FRANGE_PATTERN)
  
  # Regular expression for padding a frame range.
  PAD_PATTERN = r"(-?)(\d+)(?:(-)(-?)(\d+)(?:([:xy]{1})(\d+))?)?"
  PAD_RE = re.compile(PAD_PATTERN)
  