lib/toughguy/query.rb
def map(key = nil, &block)
      m = []
      key ? each {|d| m << d[key]} : each {|d| m << block[d]}
      m
    end
def map(key = nil, &block)
      m = []
      key ? each {|d| m << d[key]} : each {|d| m << block[d]}
      m
    end
Extend map to accept key argument, allowing stuff like:
   map(:path) # equivalent to map {|d| d[:path]}