Function: self
Section: programming/specific
C-Name: pari_self
Prototype: m
Help: self(): return the calling function or closure. Useful for defining
 anonymous recursive functions.
Doc: return the calling function or closure as a \typ{CLOSURE} object.
 This is useful for defining anonymous recursive functions.
 \bprog
 ? (n->if(n==0,1,n*self()(n-1)))(5)
 %1 = 120
 @eprog
