[Parser] Expressions containing in are not parsed properly (new parser) #780

❯ cat examples/expr2.py
def has(a, b):
    return a in b

❯ lpy --show-ast examples/expr2.py --tree  # Old Parser
└-Module
  |-body=↧
  | └-FunctionDef
  |   |-name=has
  |   |-args=
  |   | |-posonlyargs=↧
  |   | |-args=↧
  |   | | |-
  |   | | | |-arg=a
  |   | | | |-annotation=()
  |   | | | └-type_comment=()
  |   | | └-
  |   | |   |-arg=b
  |   | |   |-annotation=()
  |   | |   └-type_comment=()
  |   | |-vararg=↧
  |   | |-kwonlyargs=↧
  |   | |-kw_defaults=↧
  |   | |-kwarg=↧
  |   | └-defaults=↧
  |   |-body=↧
  |   | └-Return
  |   |   └-value=Compare
  |   |     |-left=Name
  |   |     | |-id=a
  |   |     | └-expr_contextType=Load
  |   |     |-cmpopType=In
  |   |     └-comparators=↧
  |   |       └-Name
  |   |         |-id=b
  |   |         └-expr_contextType=Load
  |   |-decorator_list=↧
  |   |-returns=()
  |   └-type_comment=()
  └-type_ignores=↧

❯ lpy --show-ast --new-parser examples/expr2.py --tree  # New Parser
syntax error: Token 'in' is unexpected here
 --> examples/expr2.py:2:14
  |
2 |     return a in b
  |              ^^


Note: if any of the above error or warning messages are not clear or are lacking
context please report it to us (we consider that a bug that needs to be fixed).