| instance methods | 
| [ ] | prc[ [params]* ]
        -> anObject | 
 | Synonym for Proc.call. | | arity | prc.arity -> anInteger | 
 | Returns the number of arguments required by the block. If the
      block takes no arguments, returns -1. If it takes one argument,
      returns -2. Otherwise, returns a positive argument count unless
      the last argument is prefixed with *, in which case the argument 
      count is negated. The number of required arguments is
      anInteger for positive values, and (anInteger+1).absotherwise.
  | Proc.new {||}.arity | » | 0 |  
  | Proc.new {|a|}.arity | » | -1 |  
  | Proc.new {|a,b|}.arity | » | 2 |  
  | Proc.new {|a,b,c|}.arity | » | 3 |  
  | Proc.new {|*a|}.arity | » | -1 |  
  | Proc.new {|a,*b|}.arity | » | -2 |  | | call | prc.call( [params]* )
        -> anObject | 
 | Invokes the block, setting the block's parameters to the values
      in params using the same rules as used by parallel
      assignment. Returns the value of the last expression evaluated
      in the block. 
| aProc = Proc.new {|a, *b| b.collect {|i| i*a }} |  
  | aProc.call(9, 1, 2, 3) | » | [9, 18, 27] |  
  | aProc[9, 1, 2, 3] | » | [9, 18, 27] |  |