Conditions used in annotations.

A condition is a function that takes a value and an optional context map as parameters
and returns a result map. The context map contains extra data that is passed as input. The
result map will be empty if the conditiong is satisfied (indicating success). Otherwise, it will
have at least one of the keys `:warnings` and `:errors`. These keys will map to a sequence
of warning and error message strings respectively.

Access and manipulate annotations.

Annotations are arbitrary properties associated with values that can be used for a
variety of use cases. Typically you define a "schema" using `defschema` specifying its
attributes Each of the schemas and attributes can have arbitrary properties - key/value
pairs - associated with them.

This namespace provides functions and macros to define and access annotations.

Validations based on annotations.