Indentation has no effect on program logic—it is simply used to align program lines to aid readability. In Python, however, indentation is used to associate and group statements.
- A header in Python is a specific keyword followed by a colon.
- The set of statements following a header in Python is called a suite (commonly called a block).
- The statements of a given suite must all be indented the same amount.
- A header and its associated suite are together referred to as a clause.
- A compound statement in Python may consist of one or more clauses. While four spaces are commonly used for each level of indentation, any number of spaces may be used.
- In (a), both suites maintain the same level of indentation.
- In (b), each suite has varying levels of indentation. This is syntactically correct, although it's not recommended practice. The key point is that the indentation within each suite remains consistent.
- In (c), the if and else headers of the if statement aren't indented at the same level.
- In (d), the headers have the same indentation, but the statements within the second suite lack proper alignment.