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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def coltype_as_typeengine(coltype: Union[VisitableType, TypeEngine]) -> TypeEngine: """ Instances of SQLAlchemy column types are subclasses of ``TypeEngine``. It's possible to specify column types either as such instances, or as the class type. This function ensures that such classes are converted to instances. To explain: you can specify columns like .. code-block:: python a = Column("a", Integer) b = Column("b", Integer()) c = Column("c", String(length=50)) isinstance(Integer, TypeEngine) # False isinstance(Integer(), TypeEngine) # True isinstance(String(length=50), TypeEngine) # True type(Integer) # <class 'sqlalchemy.sql.visitors.VisitableType'> type(Integer()) # <class 'sqlalchemy.sql.sqltypes.Integer'> type(String) # <class 'sqlalchemy.sql.visitors.VisitableType'> type(String(length=50)) # <class 'sqlalchemy.sql.sqltypes.String'> This function coerces things to a :class:`TypeEngine`. """

    if isinstance(coltype, TypeEngine):
        return coltype
    return coltype()