NeuroML is an international, collaborative initiative to develop a language for describing detailed models of neural systems, which will serve as a standard data format for defining and exchanging descriptions of neuronal cell and network models. NeuroML is:

• modular
• standardised
• structured

and this allows you to:

• easily build detailed models of neural systems
• easily validate your models
• easily visualise your models
• easily simulate your models using a variety of simulators
• easily analyse your simulations

all using a well supported set of tools in the powerful Python programming language.

https://docs.neuroml.org

For an overview of the core NeuroML repositories and the status of tests on these see here.