Formal parameter list AST node.
EBNF grammar:
formal-parameter-list:
fixed-parameters
fixed-parameters "," parameter-array-or-arglist
parameter-array-or-arglist
fixed-parameters:
fixed-parameter ( "," fixed-parameter )*
fixed-parameter:
(attributes)? (parameter-modifier)? type identifier
parameter-modifier:
"ref"
"out"
parameter-array-or-arglist:
parameter-array
arglist-parameter
parameter-array:
(attributes)? "params" array-type identifier
arglist-parameter:
__arglist