check_encoding (REXML::Encoding)

    # File rexml/encoding.rb, line 28
      def check_encoding str
    			rv = ENCODING_CLAIMS.find{|k,v| str =~ k }
    			# Raise an exception if there is a declared encoding and we don't
    			# recognize it
    			unless rv
    				if str =~ /^\s*<?xml\s*version=(['"]).*?\1\s*encoding=(["'])(.*?)\2/
    					raise "A matching encoding handler was not found for encoding '#{$3}', or the encoding handler failed to load due to a missing support library (such as uconv)."
    				else
    					return UTF_8
    				end
    			end
    			return rv[1]
    		end