## Description

lookup(M,A) -- provides the unary method named

M for class

A. The first place to look is

A#M. The search proceeds with the parent of

A, and so on.

lookup(M,A,B) -- provides the binary method named

M for

(A,B). The first place to look is

Y#(M,A,B) where

Y is the younger of

A and

B. The search proceeds next with the parent of

B, and so on.

lookup(M,A,B,C) -- provides the ternary method named

M for

(A,B,C). The first place to look is

Y#(M,A,B,C) where

Y is the youngest of

A,

B, and

C. The search proceeds with the parent of

C, and so on.

lookup(M,A,B,C,D) -- provides the quaternary method named

M for

(A,B,C,D). The first place to look is

Y#(M,A,B,C,D) where

Y is the youngest of

A,

B,

C, and

D. The search proceeds with the parent of

D, and so on.

lookup x -- where

x is a symbol or function, returns

x.

If no method is found, then

null is returned.