Thanks.
However, unfortunately, this warning seems impossible to suppress.

Use following example:

  import warnings
  warnings.filterwarnings('ignore')

  warnings.warn(SyntaxWarning("test"))

  def f(x):
    return x is 5

  print(f(5))

I succeeded in suppressing my own  SyntaxWarning("test") , but the output is still:
  
  python a.py
  a.py:7: SyntaxWarning: "is" with a literal. Did you mean "=="?
    return x is 5
  True