introduced python' syntax model in now that we're stepping up to larger statements like ifthis section reviews and expands on the syntax ideas introduced earlier in generalpython has simplestatement-based syntax howeverthere are few properties you need to know aboutstatements execute one after anotheruntil you say otherwise python normally runs statements in file or nested block in order from first to last as sequencebut statements like if (as well as loops and exceptionscause the interpreter to jump around in your code because python' path through program is called the control flowstatements such as if that affect it are often called controlflow statements block and statement boundaries are detected automatically as we've seenthere are no braces or "begin/enddelimiters around blocks of code in pythoninsteadpython uses the indentation of statements under header to group the statements in nested block similarlypython statements are not normally terminated with semicolonsratherthe end of line usually marks the end of the statement coded on that line as special casestatements can span lines and be combined on line with special syntax compound statements header ":indented statements all python compound statements--those with nested statements--follow the same patterna header line terminated with colonfollowed by one or more nested statementsusually indented under the header the indented statements are called block (or sometimesa suitein the if statementthe elif and else clauses are part of the ifbut they are also header lines with nested blocks of their own as special caseblocks can show up on the same line as the header if they are simple noncompound code blank linesspacesand comments are usually ignored blank lines are both optional and ignored in files (but not at the interactive promptwhen they terminate compound statementsspaces inside statements and expressions are almost always ignored (except in string literalsand when used for indentationcomments are always ignoredthey start with character (not inside string literaland extend to the end of the current line docstrings are ignored but are saved and displayed by tools python supports an additional comment form called documentation strings (docstrings for short)whichunlike commentsare retained at runtime for inspection docstrings are simply strings that show up at the top of program files and some statements python ignores their contentsbut they are automatically attached to objects at runtime and may be displayed with documentation tools like pydoc docstrings are part of python' larger documentation strategy and are covered in the last in this part of the book python syntax revisited