code: def _qualify_map(key, content):
      
      if not isinstance(key, basestring):
          return key, content
  
      min_len  = None
      max_len  = None
      modifier = []
      m        = RE_MATCH_CSTR(key)
  
      if not m:
          raise KeyError("Unable to parse, invalid key: %r" % key)
  
      if m.group(3) is not None:
          min_len = max_len = int(m.group(3))
      elif m.group(4) is not None:
          if m.group(4):
              min_len = int(m.group(4))
          else:
              min_len = 0
          if m.group(5):
              max_len = int(m.group(5))
      elif m.group(6) == '*':
          min_len = 0
      elif m.group(6) == '+':
          min_len = 1
      elif m.group(6) == '?':
          min_len = 0
          max_len = 1
  
      if m.group(7):
          modifier = m.group(7).split(',')
  
      if m.group(8) == '-':
          modifier.append('strip')
  
      if m.group(2) == '*':
          return m.group(1), OptionalNull(content, min_len, max_len, modifier)
      elif m.group(2) == '?':
          return m.group(1), Optional(content, min_len, max_len, modifier)
      elif m.group(2) == '+':
          return m.group(1), Mandatory(content, min_len, max_len, modifier)
      else:
          return m.group(1), Mandatory(content, min_len, max_len, modifier)
docs: When a dictionary key is optional/optionalnull/mandatory, its corresponding
      _value_ is decorated in an Optional/OptionalNull/Mandatory tuple.
      This function undo the decoration when necessary.