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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_valid_group(group_name, nova_creds):
 """ Checks to see if the configuration file contains a SUPERNOVA_GROUP configuration option. """

    valid_groups = []
    for key, value in nova_creds.items():
        supernova_groups = value.get('SUPERNOVA_GROUP', [])
        if hasattr(supernova_groups, 'startswith'):
            supernova_groups = [supernova_groups]
        valid_groups.extend(supernova_groups)
    valid_groups.append('all')
    if group_name in valid_groups:
        return True
    else:
        return False