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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 v_reference_leaf_leafref(ctx, stmt):
 """Verify that all leafrefs in a leaf or leaf-list have correct path"""


    if (hasattr(stmt, 'i_leafref') and
        stmt.i_leafref is not None and
        stmt.i_leafref_expanded is False):
        path_type_spec = stmt.i_leafref
        not_req_inst = not(path_type_spec.require_instance)
        x = validate_leafref_path(ctx, stmt,
                                  path_type_spec.path_spec,
                                  path_type_spec.path_,
                                  accept_non_config_target=not_req_inst
        )
        if x is None:
            return
        ptr, expanded_path, path_list = x
        path_type_spec.i_target_node = ptr
        path_type_spec.i_expanded_path = expanded_path
        path_type_spec.i_path_list = path_list
        stmt.i_leafref_expanded = True
        if ptr is not None:
            chk_status(ctx, stmt, ptr)
            stmt.i_leafref_ptr = (ptr, path_type_spec.pos)