def is_valid_lval(t):
 if ((not is_internal(t)) and is_lval(t) and (t not in RESERVED_NAMES)):
  return True
 return False

def is_valid_lval ( t ) : if ( ( not is_internal ( t ) ) and is_lval ( t ) and ( t not in RESERVED_NAMES ) ) : return True return False
checks whether t is valid js identifier name also returns false on internal .