break
		}
		if b == "" || strings.HasPrefix(b, " ") {
			return false // not followed by non-space
		}
	}

	return true
}

// oldHeading returns the *Heading for the given old-style section heading line.
func (d *parseDoc) oldHeading(line string) Block {
	return &Heading{Text: []Text{Plain(strings.TrimSpace(line))}}
}

// isHeading reports whether line is a new-style section heading.