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+:mod:`email`: Iterators
+-----------------------
+
+.. module:: email.iterators
+   :synopsis: Iterate over a  message object tree.
+
+
+Iterating over a message object tree is fairly easy with the
+:meth:`Message.walk` method.  The :mod:`email.iterators` module provides some
+useful higher level iterations over message object trees.
+
+
+.. function:: body_line_iterator(msg[, decode])
+
+   This iterates over all the payloads in all the subparts of *msg*, returning the
+   string payloads line-by-line.  It skips over all the subpart headers, and it
+   skips over any subpart with a payload that isn't a Python string.  This is
+   somewhat equivalent to reading the flat text representation of the message from
+   a file using :meth:`readline`, skipping over all the intervening headers.
+
+   Optional *decode* is passed through to :meth:`Message.get_payload`.
+
+
+.. function:: typed_subpart_iterator(msg[, maintype[, subtype]])
+
+   This iterates over all the subparts of *msg*, returning only those subparts that
+   match the MIME type specified by *maintype* and *subtype*.
+
+   Note that *subtype* is optional; if omitted, then subpart MIME type matching is
+   done only with the main type.  *maintype* is optional too; it defaults to
+   :mimetype:`text`.
+
+   Thus, by default :func:`typed_subpart_iterator` returns each subpart that has a
+   MIME type of :mimetype:`text/\*`.
+
+The following function has been added as a useful debugging tool.  It should
+*not* be considered part of the supported public interface for the package.
+
+
+.. function:: _structure(msg[, fp[, level]])
+
+   Prints an indented representation of the content types of the message object
+   structure.  For example::
+
+      >>> msg = email.message_from_file(somefile)
+      >>> _structure(msg)
+      multipart/mixed
+          text/plain
+          text/plain
+          multipart/digest
+              message/rfc822
+                  text/plain
+              message/rfc822
+                  text/plain
+              message/rfc822
+                  text/plain
+              message/rfc822
+                  text/plain
+              message/rfc822
+                  text/plain
+          text/plain
+
+   Optional *fp* is a file-like object to print the output to.  It must be suitable
+   for Python's extended print statement.  *level* is used internally.
+