| :mod:`symbol` --- Constants used with Python parse trees | 
 | ======================================================== | 
 |  | 
 | .. module:: symbol | 
 |    :synopsis: Constants representing internal nodes of the parse tree. | 
 | .. sectionauthor:: Fred L. Drake, Jr. <fdrake@acm.org> | 
 |  | 
 | **Source code:** :source:`Lib/symbol.py` | 
 |  | 
 | -------------- | 
 |  | 
 | This module provides constants which represent the numeric values of internal | 
 | nodes of the parse tree.  Unlike most Python constants, these use lower-case | 
 | names.  Refer to the file :file:`Grammar/Grammar` in the Python distribution for | 
 | the definitions of the names in the context of the language grammar.  The | 
 | specific numeric values which the names map to may change between Python | 
 | versions. | 
 |  | 
 | This module also provides one additional data object: | 
 |  | 
 |  | 
 | .. data:: sym_name | 
 |  | 
 |    Dictionary mapping the numeric values of the constants defined in this module | 
 |    back to name strings, allowing more human-readable representation of parse trees | 
 |    to be generated. |