if h.Stderr != nil {
		return h.Stderr
	}
	return os.Stderr
}

// removeLeadingDuplicates remove leading duplicate in environments.
// It's possible to override environment like following.
//
//	cgi.Handler{
//	  ...
//	  Env: []string{"SCRIPT_FILENAME=foo.php"},
//	}
func removeLeadingDuplicates(env []string) (ret []string) {
	for i, e := range env {
		found := false

		},
		{
			env:  []string{"a=b", "b=c", "d", "e=f"},
			want: []string{"a=b", "b=c", "d", "e=f"},
		},
	}
	for _, tt := range tests {
		got := removeLeadingDuplicates(tt.env)
		if !reflect.DeepEqual(got, tt.want) {
			t.Errorf("removeLeadingDuplicates(%q) = %q; want %q", tt.env, got, tt.want)
		}
	}