The code examples below assume this snippet as a prefix:

from css.parse import parse
data = """
    em {
    padding: 2px; 
    margin: 1em;
    border-width: medium;
    border-style: dashed;
    line-height: 2.4em;
    }
    p { color: red; font-size: 12pt }
    p:first-letter { color: green; font-size: 200% }
    p:first-line { color: blue }"""

Iterating an entire stylesheet.

A Stylesheet instance can be iterated to yield each rule, including @charset and @import rules, in the order they originally appear.

for rule in parse(data):
    print rule
    # or do something with each rule

Iterating the declarations of a single rule.

Rules that contain other rules, such as a Media or Page instances yield their child rules. A Ruleset instance yields its declarations.

for decl in parse(data)[0]:
    print decl
    # or do something else with each declaration