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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def patch_f90_compiler(f90_compiler):
 """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. """

    # 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)