Arithmetic expression parser library. Embed customized expression evaluation
into your application or library. Example uses:
* Safely process an expression entered through a web application, for example
  some formula to be plotted. The library allows safe translation of such
  expression without exposing any application's internals
* precompiler that checks for allowed and denied identifiers in an expression
* have a common expression language through your application regardless of the
  backend languages
* compile arithmetic expression to any other expression tree (semantic), for
  example SQLAlchemy expression objects