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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 readInstanceTag(instanceID, tagName="Name", connection=None):
 """ Load a tag from EC2 :param str instanceID: Instance ID to read the tag on :param str tagName: Name of tag to load :param connection: optional boto connection to use :returns: the tag's value :rtype: str """

  assert isinstance(instanceID, basestring), ("instanceID must be a string but is %r" % instanceID)
  assert isinstance(tagName, basestring), ("tagName must be a string but is %r" % tagName)

  if not connection:
    # Assume AWS credentials are in the environment or the instance is using an IAM role
    connection = boto.ec2.connect_to_region(myRegion())

  # Filter the tag values for our instance_id
  # http://docs.aws.amazon.com/AWSEC2/latest/CommandLineReference/ApiReference-cmd-DescribeTags.html
  tagData = connection.get_all_tags(filters={"resource-id": instanceID, "key": tagName})
  if tagData:
    tagValue = tagData[0].value
  else:
    raise RuntimeError, "%s: No such tag on %s" % (tagName, instanceID)
  return tagValue