_query method has odd returns

[TomFaulkner]

_query method returns an output or false, this is likely better handled by an exception

The query method is used in many functions, would add a lot of exception handling. Perhaps return a boolean and the value / empty string

[TomFaulkner]

Perhaps include a retry or two on queries as well. Though, this would slow things down if sending irrelevant queries to a device.