SUMMARY: Biological Expression Language (BEL) assembles knowledge networks from 
biological relations across multiple modes and scales. Here, we present PyBEL; a 
software package for parsing, validating, converting, storing, querying, and 
visualizing networks encoded in BEL.
AVAILABILITY AND IMPLEMENTATION: PyBEL is implemented in platform-independent, 
universal Python code. Its source is distributed under the Apache 2.0 License at 
https://github.com/pybel.
CONTACT: charles.hoyt@scai.fraunhofer.de.
SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics 
online.