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File: //opt/alt/python37/lib64/python3.7/site-packages/sqlalchemy/sql/__pycache__/visitors.cpython-37.pyc
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�Zdd�Zdd�Zdd�Zdd�Zd d�ZdS)!aOVisitor/traversal interface and library functions.

SQLAlchemy schema and expression constructs rely on a Python-centric
version of the classic "visitor" pattern as the primary way in which
they apply functionality.  The most common use of this pattern
is statement compilation, where individual expression classes match
up to rendering methods that produce a string result.   Beyond this,
the visitor system is also used to inspect expressions for various
information and patterns, as well as for usage in
some kinds of expression transformation.  Other kinds of transformation
use a non-visitor traversal system.

For many examples of how the visit system is used, see the
sqlalchemy.sql.util and the sqlalchemy.sql.compiler modules.
For an introduction to clause adaption, see
http://techspot.zzzeek.org/2008/01/23/expression-transformations/

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