/// identifies brace insets
InsetMathBrace * asBraceInset() { return this; }
/// identifies brace insets
InsetMathBrace const * asBraceInset() const { return this; }
/// identifies brace insets
InsetMathBrace * asBraceInset() { return this; }
/// identifies brace insets
InsetMathBrace const * asBraceInset() const { return this; }