$content =~ s{ ^ ( \\newline \ )+ }{ _lb_to_space($1) }gxe; # convert line breaks at the start of the text to vertical space
$content =~ s{ ( \n\n+ ) ( \\newline \ )+ }{ $1 . _lb_to_space($2) }gxe; # convert line breaks at the start of a paragraph to vertical space
$content =~ s{ ( \\end\{ [^\}]+ \} \h* ) ( \\newline \ )+ }{ $1 . _lb_to_space($2) }gxe; # convert line breaks after LaTeX environments like lists to vertical space
$content =~ s{ ^ ( \\newline \ )+ }{ _lb_to_space($1) }gxe; # convert line breaks at the start of the text to vertical space
$content =~ s{ ( \n\n+ ) ( \\newline \ )+ }{ $1 . _lb_to_space($2) }gxe; # convert line breaks at the start of a paragraph to vertical space
$content =~ s{ ( \\end\{ [^\}]+ \} \h* ) ( \\newline \ )+ }{ $1 . _lb_to_space($2) }gxe; # convert line breaks after LaTeX environments like lists to vertical space