Typography Unit Converter

def typography_converter(value: float, from_unit: str, to_unit: str,
                           dpi: float = 96, base_font_px: float = 16) -> float:
    """Convert between typography units. Returns converted value."""
    # Convert to px first
    to_px = {
        'px':   lambda v: v,
        'pt':   lambda v: v * dpi / 72,
        'pc':   lambda v: v * dpi / 6,
        'em':   lambda v: v * base_font_px,
        'rem':  lambda v: v * base_font_px,
        'mm':   lambda v: v * dpi / 25.4,
        'cm':   lambda v: v * dpi / 2.54,
        'in':   lambda v: v * dpi,
        'ex':   lambda v: v * base_font_px * 0.5,
        'ch':   lambda v: v * base_font_px * 0.5,
    }
    from_px = {
        'px':   lambda v: v,
        'pt':   lambda v: v * 72 / dpi,
        'pc':   lambda v: v * 6 / dpi,
        'em':   lambda v: v / base_font_px,
        'rem':  lambda v: v / base_font_px,
        'mm':   lambda v: v * 25.4 / dpi,
        'cm':   lambda v: v * 2.54 / dpi,
        'in':   lambda v: v / dpi,
        'ex':   lambda v: v / (base_font_px * 0.5),
        'ch':   lambda v: v / (base_font_px * 0.5),
    }
    px = to_px[from_unit](value)
    return from_px[to_unit](px)

# Examples
print(f"16px = {typography_converter(16, 'px', 'pt'):.4f}pt at 96dpi")
print(f"1em = {typography_converter(1, 'em', 'px'):.4f}px at base 16px")
print(f"12pt = {typography_converter(12, 'pt', 'px'):.4f}px at 96dpi")
print(f"1in = {typography_converter(1, 'in', 'pt'):.4f}pt")