exec_stmt: "exec" expression ["in" expression ["," expression]]
This statement supports dynamic execution of Python code. The first expression should evaluate to either a string, an open file object, or a code object. If it is a string, the string is parsed as a suite of Python statements which is then executed (unless a syntax error occurs). If it is an open file, the file is parsed until EOF and executed. If it is a code object, it is simply executed.
In all cases, if the optional parts are omitted, the code is executed
in the current scope. If only the first expression after in is
specified, it should be a dictionary, which will be used for both the
global and the local variables. If two expressions are given, both
must be dictionaries and they are used for the global and local
variables, respectively.
Note: dynamic evaluation of expressions is supported by the built-in
function eval.