LocalVariableStack addVariable(String name, PyExpr varExpression) {
    Preconditions.checkState(!localVarExprs.isEmpty());
    localVarExprs.peek().put(name, varExpression);
    return this;
  }
LocalVariableStack addVariable ( String name , PyExpr varExpression ) { Preconditions . checkState ( ! localVarExprs . isEmpty ( ) ) ; localVarExprs . peek ( ) . put ( name , varExpression ) ; return this ; }
Adds a variable to the current reference frame.

@param name The name of the variable as used by calling expressions.
@param varExpression The underlying expression used to access the variable.
@return A reference to this object.