In Python, you can use the from module import * statement to bring in all definitions from a module into the current namespace. However, it is generally recommended to use import module or from module import name to import specific functions or classes from a module.

In the unittest framework, the assertEqual method is used to compare whether two values are equal. It is commonly used within test cases to verify that the actual output matches the expected output. If the values are not equal, it raises an assertion error.

In the unittest framework, the fail() method is used to immediately terminate a test and mark it as failed. This is useful when you want to explicitly indicate a test failure.

The classmethod function in the functools module is used to transform a method into a class method decorator. Class methods can be called on the class itself rather than on instances of the class.

In Python, the 'if' keyword is used to define conditions for conditional execution of code blocks. Code within an 'if' block is executed only if the specified condition evaluates to true.

The __new__ method in a metaclass is called when a new object is created from a class. This method is responsible for creating and returning a new instance of the class.

The send method is used to resume a generator and send a value back to it. This is commonly used for implementing two-way communication with a generator.

In Pandas DataFrame, the reorder_columns() method is used to rearrange the order of the DataFrame's columns. This method allows you to specify the new order of columns using a list or other methods like loc.

In Pandas, the drop method is used to drop specified labels (rows or columns) from a DataFrame. This method provides options to control whether the operation should be performed in place or return a new DataFrame.

The "constructor" method in Python is used to initialize a newly created object and is called every time the class is instantiated. This method is typically named __init__ in Python classes.