arg(x) looks in the calling environment for the binding x,
taken literally, and returns it as a quotation. arg(x) is
equivalent to unwrap(quo(x)).
arg_ evaluates the first element normally;
arg(x, e) is equivalent to arg_(quote(x), e).
arg_list looks up multiple variables, and returns a dots
object.  arg_list(x, y) is equivalent to unwrap(dots(x=x, y=y)). If any of the requested variables are not bound, an error
will be raised.
arg_list_ is a normally evaluating version of arg_list;
arg_list(x, y) is equivalent to
arg_list_(alist(x, y), environment()).
set_arg and set_arg_ create bindings from quotations. They
replace base function delayedAssign.
arg(sym, env = arg_env_(quote(sym), environment()))arg_(sym, env = arg_env(sym, environment()))
arg_list(...)
arg_list_(syms, envs)
set_arg(dst, src)
set_arg_(dst, src)
The name to look up. For arg this is a literal name,
not evaluated. For arg_ this should evaluate to a symbol or
character.
The environment to look in. By default, the environment
from which sym was passed.
Bare names (not forced). Arguments may be named; these names determine the names on the output list. If argument names are not given, the input is used as output names
A character vector or list of names.
An environment, or a list of environments, to look for the bindings in.
A name; for set_arg this is quoted literally; for
set_arg_ this should be a quotation.
A quotation (or something that can be converted to a quotation, like a formula).
arg returns a quotation object.
args returns a dots object.
arg_list returns a dots object.
dots get_dots unwrap