curl -O https://hyperledger.github.io/composer/latest/prereqs-ubuntu.sh
chmod u+x prereqs-ubuntu.sh
./prereqs-ubuntu.sh
npm install -g composer-cli@0.20
npm install -g composer-rest-server@0.20
npm install -g generator-hyperledger-composer@0.20
npm install -g yo
npm install -g composer-playground
composer-playground
https://hyperledger.github.io/composer/v0.19/installing/installing-prereqs