What role is played by file modes in file operations ? Describe the various file mode constants and their meanings.

File modes play a crucial role in file operations in Python as they determine how the file will be opened and what operations can be performed on it. Each file mode specifies whether the file should be opened for reading, writing, appending, or a combination of these operations. Additionally, file modes can distinguish between text mode and binary mode, which affects how the file data is handled.

Here are the various text file mode constants in Python and their meanings:

1. "r" — Opens the file for reading only. This is the default mode if no mode is specified.
2. "w" — Opens the file for writing only.
3. "a" — Opens the file for writing, but appends new data to the end of the file.
4. "r+" — Opens the file for both reading and writing.
5. "w+" — Opens the file for writing and reading.
6. "a+" — Opens the file for reading and appending.

Here are the various binary file mode constants in Python and their meanings:

"rb", "wb", "ab", "rb+", "wb+", "ab+" — These modes are similar to their corresponding text modes ("r", "w", "a", "r+", "w+", "a+"), but they operate in binary mode.