'Hierarchical tree of words classified by semantic type.
For example: "rose" and "daffodil" can be classified as "flower":
>>> taxonomy.append("rose", type="flower")
>>> taxonomy.append("daffodil", type="flower")
>>> print(taxonomy.children("flower"))
Taxonomy terms can be used in a Pattern:
FLOWER will match "flower" as well as "rose" and "daffodil".
The taxonomy is case insensitive by default.'

def __init__(self):

    self.case_sensitive = False
    self._values = {}
    self.classifiers = []
