anchor.diff:  #,\def\specialFrac#1#2{\frac{x + #1}{y + #2}}
   %,%this is a single-line comment
   &,"\begin{matrix}
  -    a & b\cr
  -    c & d
  -    \end{matrix}"
  +a & b\cr
  +c & d
  +\end{matrix}"
   ^,x^i
   _,x_i
   {,\{
  
positive.code: \large,{\large AaBb123}
  \lbrace,
  \lceil,
  \ldots,
  \leadsto,
  \left,\left\lbrace \frac ab, c \right\rbrace
  \leftarrow,
  
negative.code: \Doteq,
  \doteqdot,
  \dotplus,
  \dots,"\begin{array}{c}
  x_1, \dots, x_n \cr
  x_1 + \dots + x_n
  \end{array}"
  \cdots,
  \ldots,
  \dotsb,"\begin{array}{c}
  \text{dots with binary operations and relations:} \cr\cr
  x_1 + x_2 +\dotsb + x_n \cr
  x_1 + x_2 +\dotsb + x_n
  \end{array}"
  \dotsc,"\begin{array}{c}
  \text{dots with commas:} \cr\cr
  x_1,x_2,\dotsc,x_n \cr
  x_1,x_2,\dots,x_n
  \end{array}"
  \dotsi,"\begin{array}{c}
  \text{dots with integrals:} \cr\cr
  \int_{A_1}\int_{A_2}\dotsi\int_{A_n} \cr
  \int_{A_1}\int_{A_2}\dots\int_{A_n}
  \end{array}"
  \dotsm,"\begin{array}{c}
  \text{dots with multiplication:} \cr\cr
  x_1x_2\dotsm x_n \cr
  x_1x_2\dots x_n
  \end{array}"
  \dotso,"\begin{array}{c}
  \text{other dots:} \cr\cr
  A_1\dotso A_n \cr
  A_1\dots A_n
  \end{array}"
  \doublebarwedge,
  \doublecap,
  \doublecup,
  