 
 #-----------------------------------------------------------------------------------------------------------
 @map_last = ( method ) ->
-  throw new Error "expected a function, got a #{type}" unless ( type = CND.type_of method ) is 'function'
-  throw new Error "method arity #{arity} not implemented" unless ( arity = method.length ) is 1
+  throw new Error "µ14003 expected a function, got a #{type}" unless ( type = CND.type_of method ) is 'function'
+  throw new Error "µ14768 method arity #{arity} not implemented" unless ( arity = method.length ) is 1
   throw new Error 'meh'
 
 #-----------------------------------------------------------------------------------------------------------
 @filter = ( method ) ->
-  throw new Error "expected a function, got a #{type}" unless ( type = CND.type_of method ) is 'function'
+  throw new Error "µ15533 expected a function, got a #{type}" unless ( type = CND.type_of method ) is 'function'
   switch arity = method.length
     when 1 then null
-    else throw new Error "method arity #{arity} not implemented"
+    else throw new Error "µ16298 method arity #{arity} not implemented"
   #.........................................................................................................
   return pull.filter method
 
 #-----------------------------------------------------------------------------------------------------------
 @map = ( method ) ->
-  throw new Error "expected a function, got a #{type}" unless ( type = CND.type_of method ) is 'function'
+  throw new Error "µ17063 expected a function, got a #{type}" unless ( type = CND.type_of method ) is 'function'
   switch arity = method.length
     when 1 then null
-    else throw new Error "method arity #{arity} not implemented"
+    else throw new Error "µ17828 method arity #{arity} not implemented"
   #.........................................................................................................
   return @_map_errors method
 

@$sample = ( p = 0.5, options ) ->
  #.........................................................................................................
  unless 0 <= p <= 1
    throw new Error "expected a number between 0 and 1, got #{rpr p}"
  #.........................................................................................................
  ### Handle trivial edge cases faster (hopefully): ###
  return ( @map     ( record ) => record  ) if p == 1

      direction = settings[ 'direction' ] ? 'ascending'
      sorter    = settings[ 'sorter'    ] ? null
      key       = settings[ 'key'       ] ? null
    else throw new Error "µ33893 expected 0 or 1 arguments, got #{arity}"
  #.........................................................................................................
  unless direction in [ 'ascending', 'descending', ]
    throw new Error "µ34658 expected 'ascending' or 'descending' for direction, got #{rpr direction}"
  #.........................................................................................................
  unless sorter?
    #.......................................................................................................
