def filter_line(line):
    """Filter input .pb.go line to ignore non-problematic differences."""
    # Strip the compiler and plugin version numbers. The expected lines
    # look like:
    #
    #   // <tab>protoc-gen-go v1.26.0\n
    #   // <tab>protoc        v3.12.4\n
    #
    # Note that protoc-gen-go-grpc does not embed its version number
    # in its output, so isn't checked here.
    for version_prefix in ('// \tprotoc ', '// \tprotoc-gen-go '):
        if line.startswith(version_prefix):
            return version_prefix + '\n'

    return line