<expr> 			= <term>	{ <second_op> <term>	}
<term>			= <factor> 	{ (<prior_op> <factor> 	}
<factor>		= ['!' | '+' | '-'] <value> [<as_kw> <type>] // Here i must use another nonterminal to support conversion to other types and +- before expr, and the '!' operator for inversions.
<value> 		= <callable>
				= <const>
				= '(' <expr> ')'

<callable>		= <id>
				= <f_call>