code: public function apply(Scope $scope, GenericList $arguments) {
  		if (count($arguments) == 0) throw new \BadFunctionCallException("ValueSet: No parameters found.");
  		if (!($arguments[0] instanceof Symbol))
  			throw new \InvalidArgumentException(sprintf("ValueSet: Expected symbol as first argument, %s found instead.", substr(strtolower(strstr(get_class($arguments[0]), '\\')), 1)));	
  		if (count($arguments) < 2) throw new \BadFunctionCallException("ValueSet: A value must be provided.");
  		$value = $arguments[1]->evaluate($scope);
  		return $scope->symbols[$arguments[0]->symbol] = $value;
  	}
docs: Sets a symbol value
  Usage: (:= _var "Hello World")
  Returns: the assigned value
  (non-PHPdoc)
  @see \eMacros\Applicable::apply()