Yorick Language Reference
Variable names may consist of letters, numbers and the underscore _.
They have to start with a letter or the underscore.
var = expr redefines var as the value
var =  undefines var
Any previous value or data type of var is forgotten. The expr
can be a data type, function, file, or any other object.
The = operator is a binary operator which has the side effect
of redefining its left operand. It associates to the right, so
var1 = var2 = var3 = expr
initializes all three var to expr