    # File lib/amalgalite/database.rb, line 702
        def define_function( name, callable = nil, &block )
          p = ( callable || block ).to_proc
          raise FunctionError, "Use only mandatory or arbitrary parameters in an SQL Function, not both" if p.arity < -1
          db_function = ::Amalgalite::SQLite3::Database::Function.new( name, p )
          @api.define_function( db_function.name, db_function )
          @functions[db_function.signature] = db_function
          nil
        end