def create_node(_id, _label, _type, _shape=''):
    """Creates a node.

    Parameters:
    _id (str): unique id
    _label (str): label shown in graph
    _type (str): type of node according to schema_key_dict
    _shape (str): shape as visualized in graph
    
    """
    return {
        'data': {
            'id': _id,
            '_label': _label if _label else _id,
            '_type': _type,
            '_shape': _shape
        },
        'classes': ''
    }