Modify Strand Assignment
From NARS2000


A_{1} A_{2} ... A_{n} are all names with existing values, f is an arbitrary dyadic function, and R is a scalar or vector.  
If 1<⍴⍴R, signal a RANK ERROR.  
If R is a scalar or one element vector, its item, in combination with the value of each name, is assigned to each name, as in A_{i}←A_{i}f ⊃⍬⍴R.  
Otherwise, assume there are n names in the list:  
If n≠⍴R, signal a LENGTH ERROR.  
Otherwise, each successive item of R, in combination with the value of each successive name, is assigned to each successive name, as in A_{i}←A_{i}f i⊃R. 
For example, (A B C)⍴←⊂⍳3 is shorthand for A←A⍴⍳3 ⋄ B←B⍴⍳3 ⋄ C←C⍴⍳3. In contrast, (A B C)⍴←⍳3 is shorthand for A←A⍴1 ⋄ B←B⍴2 ⋄ C←C⍴3.