code: private Environment checkVariableDeclarations(Tuple<Decl.Variable> decls, Environment environment) {
  		for (int i = 0; i != decls.size(); ++i) {
  			environment = checkVariableDeclaration(decls.get(i), environment);
  		}
  		return environment;
  	}
docs: Type check a given sequence of variable declarations.
  
  @param decls
  @param environment
  Determines the type of all variables immediately going into this
  statement.
  @return
  @throws IOException