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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 create_skel(role):
    '''
    Create the skeleton of a dictionary or JSON file

    A dictionary is returned that contains the "molssi_bse_schema"
    key and other required keys, depending on the role

    role can be either 'component', 'element', or 'table'
    '''

    role = role.lower()
    if not role in _skeletons:
        raise RuntimeError("Role {} not found. Should be 'component', 'element', 'table', or 'metadata'")

    return copy.deepcopy(_skeletons[role])