The function vars() returns a dictionary containing the current local variables. With a module as argument, it returns that module's global variables. The old function dir(x) returns vars(x).keys().
The function round(x) returns a floating point number rounded to the nearest integer (but still expressed as a floating point number). E.g. round(3.4) == 3.0 and round(3.5) == 4.0. With a second argument it rounds to the specified number of digits, e.g. round(math.pi, 4) == 3.1416 or even round(123.4, -2) == 100.0.
The function hash(x) returns a hash value for an object. All object types acceptable as dictionary keys have a hash value (and it is this hash value that the dictionary implementation uses).
The function id(x) return a unique identifier for an object. For two objects x and y, id(x) == id(y) if and only if x is y. (In fact the object's address is used.)
The function hasattr(x, name) returns whether an object has an attribute with the given name (a string value). The function getattr(x, name) returns the object's attribute with the given name. The function setattr(x, name, value) assigns a value to an object's attribute with the given name. These three functions are useful if the attribute names are not known beforehand. Note that getattr(x, 'foo') is equivalent to x.foo, and setattr(x, 'foo', y) is equivalent to x.foo = y. By definition, hasattr(x, name) returns true if and only if getattr(x, name) returns without raising an exception.