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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 string_to_genomic_range(rstring):
 """ Convert a string to a genomic range :param rstring: string representing a genomic range chr1:801-900 :type rstring: :returns: object representing the string :rtype: GenomicRange """

  m = re.match('([^:]+):(\d+)-(\d+)',rstring)
  if not m: 
    sys.stderr.write("ERROR: problem with range string "+rstring+"\n")
  return GenomicRange(m.group(1),int(m.group(2)),int(m.group(3)))