code: function readSimpleToken(type, endRegex, trimRight) {
  		if (trimRight) {
  			let matchTrim = exec(/\S/g)
  			if (matchTrim) {
  				advanceTo(matchTrim.index)
  			}
  		}
  		let match = exec(endRegex)
  		if (!match) {
  			throwSyntaxError(`Unterminated ${type}`)
  		}
  		let start = getSourcePoint()
  		advanceTo(match.index)
  		let token = createContentToken(type, start)
  		advanceTo(endRegex.lastIndex)
  		return token
  	}
docs: Read a single token that has a known end
  @param {string} type
  @param {RegExp} endRegex
  @param {boolean} trimRight - ignore starting empty spaces (\s)
  @returns {Token}