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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def is_uuid4(instr):
 """A validator to confirm a string is indeed a UUID4 :param instr: input string that may be uuid4 :type instr: String :return: true if it is in UUID4 format :rtype: bool """

  v = instr.strip().replace('-','').lower()
  if len(v) != 32: return False
  if not re.match('^[0-9a-f]+$',v): return False
  if v[12] != '4': return False
  if not re.match('[89ab]',v[16]): return False
  return True