Some rules

                    Alphanumerics        Non-alphanumerics

    Literal glyphs   a    1    _        \*  \$  \.   \\   \'
    Metasyntax      \a   \1   \_         *   $   .    \    '
    Quoted glyphs   'a'  '1'  '_'       '*' '$' '.' '\\' '\''

    * All glyphs that are _, Unicode letters or numbers are *always* literal
    * Any other glyph is metasyntactic (*not* self-matching)
    * Escape metasyntax with \
    * Glyphs can be made literal by placing them in quotes
    * Double quoting glyphs makes it literal with interpolating semantics