_A_p_p_l_y _a _F_u_n_c_t_i_o_n _O_v_e_r _a _L_i_s_t
	
	     lapply(x, fun, ...)
	
	_A_r_g_u_m_e_n_t_s:
	
	           x : the list to be used.
	
	         fun : the function to be applied.  In the case of
	               functions like +, %*%, etc., the function
	               name must be quoted.
	
	         ... : optional arguments to fun.
	
	_D_e_s_c_r_i_p_t_i_o_n:
	
	     lapply returns a list of the same length as x.  Each
	     element of which is the result of applying fun to the
	     corresponding element of x.
	
	_S_e_e _A_l_s_o:
	
	     apply, sapply
	
	_E_x_a_m_p_l_e_s:
	
	     x <- list(a = 1:10, beta = exp(-3:3),
	             logic = c(T,F,F,T))
	     # compute the list mean for each list element
	     lapply(x,mean)
	     # median and quartiles for each list element
	     lapply(x, quantile, probs = 1:3/4)