function isNameChar(c, cc) {
						cc = cc || c.charCodeAt(0);
						return (
							(cc >= 97 && cc <= 122 /* a-z */) ||
							(cc >= 65 && cc <= 90 /* A-Z */) ||
							/* 
							Experimental: include cyrillic ranges 
							since some letters, similar to latin ones, can 
							accidentally appear in CSS tokens
							*/
							(cc >= 1024 && cc <= 1279) ||
							c === '&' || /* selector placeholder (LESS, SCSS) */
							c === '_' ||
							c === '<' || /* comparisons (LESS, SCSS) */
							c === '>' ||
							c === '=' ||
							c === '-'
						);
					}
Check if passed symbol is valid symbol for abbreviation expression
@param {String} ch
@return {Boolean}