STRICT_GROUPING(phoneNumber, { candidate, defaultCountry, metadata, regExpCache })
	{
		if (
			!phoneNumber.isValid() ||
			!containsOnlyValidXChars(phoneNumber, candidate, metadata) ||
			containsMoreThanOneSlashInNationalNumber(phoneNumber, candidate) ||
			!isNationalPrefixPresentIfRequired(phoneNumber, { defaultCountry, metadata })
		)
		{
			return false
		}

		return checkNumberGroupingIsValid
		(
			phoneNumber,
			candidate,
			metadata,
			allNumberGroupsRemainGrouped,
			regExpCache
		)
	}
Phone numbers accepted are "valid" and
are grouped in a possible way for this locale. For example, a US number written as
"65 02 53 00 00" and "650253 0000" are not accepted at this leniency level, whereas
"650 253 0000", "650 2530000" or "6502530000" are.
Numbers with more than one '/' symbol in the national significant number
are also dropped at this level.

Warning: This level might result in lower coverage especially for regions outside of
country code "+1". If you are not sure about which level to use,
email the discussion group libphonenumber-discuss@googlegroups.com.