'Find definitions specified by `after_cursor` and check what found
For example, for the following configuration, you can pass
``after_cursor = \'y)\'``.::
function(
x, y)
`- You want cursor to be here'

def check_definition_by_marker(self, source, after_cursor, names):

    source = textwrap.dedent(source)
    for (i, line) in enumerate(source.splitlines()):
        if (after_cursor in line):
            break
    column = (len(line) - len(after_cursor))
    defs = Script(source, (i + 1), column).goto_definitions()
    assert ([d.name for d in defs] == names)
