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PatternTest (?)

is a pattern object that stands for any expression which matches p, and on which the application of test gives True.
  • Any result for test[pval] other than True is taken to signify failure.
  • The operator ? has a high precedence. Thus _^_?t is _^(_?t) not (_^_)?t.
  • In a form such as __?test every element in the sequence matched by __ must yield True when test is applied.
Find cases of any expression which satisfies the NumberQ test:
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