Completions request; value of command field is "completions". Given a file location (file, line, col) and a prefix (which may be the empty string), return the possible completions that begin with prefix.
Object containing arguments for the command
The command to execute
Sequence number of the message
One of "request", "response", or "event"
Completions request; value of command field is "completions". Given a file location (file, line, col) and a prefix (which may be the empty string), return the possible completions that begin with prefix.