# File lib/core/facets/module/op.rb, line 64
  def -(other)
    instance_methods = instance_methods(true).map{|m| m.to_sym}
    case other
    when Array
      subtract = instance_methods & other.map{|m| m.to_sym}
    when Module
      subtract = instance_methods & other.instance_methods(true).map{|m| m.to_sym}  # false?
    when String, Symbol
      subtract = instance_methods & [other.to_sym]
    end
    base = self
    Module.new do
      include base
      subtract.each{ |x| undef_method x }
    end
  end