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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 key_pair_name(i, region, project_id, ssh_user):
 """Returns the ith default gcp_key_pair_name."""

    key_name = "{}_gcp_{}_{}_{}".format(RAY, region, project_id, ssh_user, i)
    return key_name