emulator: ERROR: No AVD specified. Use '@foo' or '-avd foo' to launch a virtual device named 'foo' code example

Example: emulator: ERROR: No AVD specified. Use '@foo' or '-avd foo' to launch a virtual device named 'foo'

/Users/janedoe/Library/Android/sdk/emulator/emulator -avd Nexus_5X_API_23 -netdelay none -netspeed full