================================================================================
Integer
================================================================================

foo = 0
foo = 42

--------------------------------------------------------------------------------

(source_file
  (assignment
    (identifier)
    (integer_literal))
  (assignment
    (identifier)
    (integer_literal)))

================================================================================
Integer (negative)
================================================================================

foo = -0
foo = -42

--------------------------------------------------------------------------------

(source_file
  (assignment
    (identifier)
    (integer_literal))
  (assignment
    (identifier)
    (integer_literal)))