Skip leading space delimiters. Parse name delimited by a space. Create a definition for name with the execution semantics defined below, with an initial value of x1 x2.
name is referred to as a "two-value".
Place cell pair x1 x2 on the stack. The value of x1 x2 is that given when name was created, until the phrase "x1 x2 TO name" is executed, causing a new cell pair x1 x2 to be assigned to name.
TO name Run-time:
Assign the cell pair x1 x2 to name.