How to use the lark.lark.Lark function in lark

def test_earley4(self):
            grammar = """
            start: A A?
            A: "a"+
            """

            l = Lark(grammar, parser='earley', lexer=LEXER)
            res = l.parse("aaa")
            assert set(res.children) == {'aa', 'a'} or res.children == ['aaa']
            # XXX TODO fix Earley to maintain correct order

def test_same_ast(self):
        "Tests that Earley and LALR parsers produce equal trees"
        g = Lark(r"""start: "(" name_list ("," "*" NAME)? ")"
                    name_list: NAME | name_list "," NAME
                    NAME: /\w+/ """, parser='lalr')
        l = g.parse('(a,b,c,*x)')

        g = Lark(r"""start: "(" name_list ("," "*" NAME)? ")"
                    name_list: NAME | name_list "," NAME
                    NAME: /\w/+ """)
        l2 = g.parse('(a,b,c,*x)')
        assert l == l2, '%s != %s' % (l.pretty(), l2.pretty())

?a : b
                    b : "x"
                 """, parser='lalr', transformer=T())
        r = g.parse("x")
        self.assertEqual( r.children, ["<b>"] )

        # Test Expand1 -&gt; Alias
        g = Lark("""start: a
                    ?a : b b -&gt; c
                    b : "x"
                 """, parser='lalr')
        r = T().transform(g.parse("xx"))
        self.assertEqual( r.children, [""] )


        g = Lark("""start: a
                    ?a : b b -&gt; c
                    b : "x"
                 """, parser='lalr', transformer=T())
        r = g.parse("xx")
        self.assertEqual( r.children, [""] )
</b>

def test_ambiguity1(self):
            grammar = """
            start: cd+ "e"

            !cd: "c"
               | "d"
               | "cd"

            """
            l = Lark(grammar, parser='earley', ambiguity='explicit', lexer=LEXER)
            ambig_tree = l.parse('cde')

            assert ambig_tree.data == '_ambig', ambig_tree
            assert len(ambig_tree.children) == 2

"""

            l = _Lark(grammar, ambiguity='resolve__antiscore_sum')
            res = l.parse('abba')
            self.assertEqual(''.join(child.data for child in res.children), 'ab_b_a_')

            grammar = """
            start: ab_ b_ a_ | indirection
            indirection: a_ bb_ a_
            a_: "a"
            b_: "b"
            ab_.1: "ab"
            bb_: "bb"
            """

            l = Lark(grammar, parser='earley', ambiguity='resolve__antiscore_sum')
            res = l.parse('abba')
            self.assertEqual(''.join(child.data for child in res.children), 'indirection')

            grammar = """
            start: ab_ b_ a_ | indirection
            indirection: a_ bb_ a_
            a_.2: "a"
            b_.1: "b"
            ab_.3: "ab"
            bb_.3: "bb"
            """

            l = Lark(grammar, parser='earley', ambiguity='resolve__antiscore_sum')
            res = l.parse('abba')
            self.assertEqual(''.join(child.data for child in res.children), 'ab_b_a_')

def A(self, tok):
                return tok.update(value=tok.upper())

        # Test regular
        g = """start: a
            a : A
            A: "x"
            """
        p = Lark(g, parser='lalr')
        r = T(False).transform(p.parse("x"))
        self.assertEqual( r.children, ["x!"] )
        r = T().transform(p.parse("x"))
        self.assertEqual( r.children, ["X!"] )

        # Test internal transformer
        p = Lark(g, parser='lalr', transformer=T())
        r = p.parse("x")
        self.assertEqual( r.children, ["X!"] )

def test_earley3(self):
            """Tests prioritization and disambiguation for pseudo-terminals (there should be only one result)

            By default, `+` should immitate regexp greedy-matching
            """
            grammar = """
            start: A A
            A: "a"+
            """

            l = Lark(grammar, parser='earley', lexer=LEXER)
            res = l.parse("aaa")
            self.assertEqual(set(res.children), {'aa', 'a'})
            # XXX TODO fix Earley to maintain correct order

def test_term_ambig_resolve(self):
            grammar = r"""
            !start: NAME+
            NAME: /\w+/
            %ignore " "
            """
            text = """foo bar"""

            parser = Lark(grammar)
            tree = parser.parse(text)
            self.assertEqual(tree.children, ['foo', 'bar'])