def METHOD_NAME(self):
    """Allows to connect data_tree1 input to the operator.
    Either a vector of data trees or data trees
    from pin 0 to ... to merge.
    Parameters
    ----------
    my_data_tree1 : DataTree
    Examples
    --------
    >>> from ansys.dpf import core as dpf
    >>> op = dpf.operators.utility.merge_data_tree()
    >>> op.inputs.data_tree1.connect(my_data_tree1)
    >>> # or
    >>> op.inputs.data_tree1(my_data_tree1)
    """
    return self._data_tree1