module Spruz::Subhash

def subhash(*patterns)

otherwise it is nil.
MatchData instance if the matching pattern was a regular rexpression
value of the block as the value of the result hash. +match_data+ is a
matched with a 3-tuple of +(key, value, match_data)+ using the return
If a block is given this method yields to it after the first pattern

to put 'foobar' and 'foobaz' or 'foo'/:foo to put 'foo' into the subhash.
matching +patterns+ and return it. +patterns+ can be for example /^foo/
Create a subhash from this hash, that only contains key-value pairs 
def subhash(*patterns)
  patterns.map! do |pat|
    pat = pat.to_sym.to_s if pat.respond_to?(:to_sym)
    pat.respond_to?(:match) ? pat : pat.to_s
  end
  result =
    if default_proc
      self.class.new(&default_proc)
    else
      self.class.new(default)
    end
  if block_given?
    each do |k, v|
      patterns.each { |pat|
        if pat === k.to_s
          result[k] = yield(k, v, $~)
          break
        end
      }
    end
  else
    each do |k, v|
      result[k] = v if patterns.any? { |pat| pat === k.to_s }
    end
  end
  result
end