code: def patch_f90_compiler(f90_compiler):
      
      # NOTE: NumPy may not be installed, but we don't want **this** module to
      #       cause an import failure in ``setup.py``.
      from numpy.distutils.fcompiler import gnu
  
      # Only ``gfortran``.
      if not isinstance(f90_compiler, gnu.Gnu95FCompiler):
          return False
  
      f90_compiler.compiler_f77[:] = _update_flags(
          f90_compiler.compiler_f77, remove_flags=("-Werror",)
      )
      f90_compiler.compiler_f90[:] = _update_flags(f90_compiler.compiler_f90)
docs: Patch up ``f90_compiler``.
  
      For now, only updates the flags for ``gfortran``. In this case, it add
      any of ``GFORTRAN_SHARED_FLAGS`` that are missing. In debug mode, it also
      adds any flags in ``GFORTRAN_DEBUG_FLAGS`` and makes sure none of the flags
      in ``GFORTRAN_OPTIMIZE_FLAGS`` are present. In standard mode ("OPTIMIZE"),
      makes sure flags in ``GFORTRAN_OPTIMIZE_FLAGS`` are present and flags in
      ``GFORTRAN_DEBUG_FLAGS`` are not.
  
      Args:
          f90_compiler (numpy.distutils.fcompiler.FCompiler): A Fortran compiler
              instance.