code: def _jit(function):
      
      import sys
  
      compiled = numba.jit(function)
  
      if hasattr(sys, '_called_from_test'):
          return function
      else:  # pragma: no cover
          return compiled
docs: Compile a function using a jit compiler.
  
      The function is always compiled to check errors, but is only used outside
      tests, so that code coverage analysis can be performed in jitted functions.
  
      The tests set sys._called_from_test in conftest.py.