Valid HK Phone Number

Overview

In Hong Kong, a valid phone number has the format xxxx xxxx where x is a decimal digit (0-9). For example:

"1234 5678" 
// is valid

"2359 1478" 
// is valid

"85748475" 
// invalid, as there are no spaces separating the first 4 and last 4 digits

"3857  4756" 
// invalid; there should be exactly 1 whitespace separating the first 4 and last 4 digits respectively

"sklfjsdklfjsf" 
// clearly invalid

"     1234 5678   " 
// is NOT a valid phone number but CONTAINS a valid phone number

"skldfjs287389274329dklfj84239029043820942904823480924293042904820482409209438dslfdjs9345 8234sdklfjsdkfjskl28394723987jsfss2343242kldjf23423423SDLKFJSLKsdklf" 
// also contains a valid HK phone number (9345 8234)

Task

Define two functions that returns whether a given string is a valid HK phone number and contains a valid HK phone number respectively (i.e. true/false values).

If in doubt please refer to the example tests.